Liquid separation system

ABSTRACT

A liquid separation purification system applicable to extracting purified liquids from or concentrating solids in a liquid feed material. The system is particularly useful for extracting potable water from sea water. Cool feed liquid is pumped through the internal passages of a surface condenser section. The feed liquid leaving the condenser section, warmed by absorption of heat of condensation, is then further heated to a temperature below the boiling point of the liquid and then transferred to an absorption section. The absorption section is formed of a matrix of material which divides the liquid into a plurality of thin films. The condenser surface and absorber matrix are positioned in an insulated housing with openings between portions of the condenser and absorber. A second non-condensing fluid (gas) circulating in the absorber is saturated with part of the heated liquid on the matrix. The gas containing part of the feed fluid is circulated so that it travels toward the cooler condenser surface which strips the absorbed part of the feed liquid from the gas and precipitates it into droplets and films to fall into a collection sump for the condensate.

United States Patent [191 Lowi, Jr. et al.

1 1 Jan. 14, 1975 LIQUID SEPARATION SYSTEM 22 Filed: .lune27, 1973 21Appl. No.: 374,211

[52] US. Cl. 202/236, 159/1 W, 159/13 R, 203/70, 203/89, 203/49 [51]Int. Cl. B01b BOld 3/00, B01d l/OO,

BOld 3/34, B01d 3/08 [58] Field of Search 159/1 W, 4 K, 13 B, 28 P,l59/DIG. 28, 8, 47 R, 24 A, 13 C; 202/236;

[56] References Cited UNITED STATES PATENTS 614,776 11/1898 Stocker202/163 1,481,723 1/1924 Merz i 159/10 1,853,330 4/1932 Barstow et a1.203/49 X 2,433,741 12/1947 Crawford 55/16 2,444,527 7/1948 Pomeroy260/4125 2,803,589 8/1957 Thomas 159/3 UX 3,248,306 4/1966 Cummings202/234 3,358,739 12/1967 Pinkerton et al. 203/49 X 3,367,787 2/1968Thijssen et a1. 159/13 C FOREIGN PATENTS OR APPLICATIONS 24,930 12/1956Germany 159/4 K 894,936 4/1962 Great Britain 159/4 K France l59/Dl(i. 28Germany 203/49 Primary Examiner lack Sofer Attorney, Agent, orFirmNilsson, Robbins, Bissell, Dalgarn & Berliner [57] ABSTRACT A liquidseparation purification system applicable to extracting purified liquidsfrom or concentrating solids in a liquid feed material. The system isparticularly useful for extracting potable water from sea water. Coolfeed liquid is pumped through the internal passages of a surfacecondenser section. The feed liquid leaving the condenser section, warmedby absorption of heat of condensation, is then further heated to atemperature below the boiling point of the liquid and then transferredto an absorption section. The absorption section is formed of a matrixof material which divides the liquid into a plurality of thin films. Thecondenser surface and absorber matrix are positioned in an insulatedhousing with openings between portions of the condenser and absorber. Asecond noncondensing fluid (gas) circulating in the absorber issaturated with part of the heated liquid on the matrix. The gascontaining part of the feed fluid is circulated so that it travelstoward the cooler condenser surface which strips the absorbedpart of thefeed liquid from the gas and precipitates it into droplets and films tofall into a collection sump for the condensate.

10 Claims, 8 Drawing Figures 44 BARRIER mi PATENTEB JAN 1 41975 SHEET 2BF 3 F165. FIG.6

EQU/L/BR/UM L/A/ES CONDENSER EVAPO/QATO/Q OPEIQAT/A/ (3O /5IOTEMPERATURE (F) LIQUID SEPARATION SYSTEM FIELD OF THE INVENTION Thefield of art to which the invention pertains includes the field ofliquid purification systems, particularly with respect to extractingpure water from an aqueous feed liquid such as sea water.

BACKGROUND OF THE INVENTION Efficient liquid separation systems requirethat a minimum of energy be expended to produce a maximum of quantityand purity of output. Conventional purification techniques involveboiling or flash evaporation of the feed liquid. A number of techniqueshave been suggested which utilize the evaporation and transfer of fluidby a stream of gas or air and subsequent condensation, and suchtechniques have been suggested for producing pure water from sea water.(See for example Hill US. Pat. No. 3,206,379.) The Hill system uses aseries of chambers providing stair step-type evaporation and cooling ofan impure liquid in each chamber. While such a system is relativelyefficient compared to prior art distillation type purification systems,the apparatus required to provide such a system is relatively complex.Due to the numerous chambers involved, the chances of breakdown of thesystem in each one of the stage chambers increases.

Known prior art includes US. Pat. Nos. 102,633; 236,940; 614,776;1,101,001; 1,225,226; 1,277,895;

The present invention overcomes the disadvantages of prior art liquidseparation systems and operates with a minimum amount of input energy topurify feed liquid. The system can be used where a small, efficient,portable purification system is required. Importantly, a single chambercan be utilized. The system does not require complex equipment and canbe easily be expanded to increase output of purified liquid.

In particular, cooled feed fluid is pumped into a heat exchanger, e.g.,a plurality of coils, of a condenser stage of the system. The liquid isthen transferred to a heating stage where it is heated and transferredto an evaporation stage consisting of a fixed bed absorption column. Anon-condensible gas is then utilized in a counterflow mode to absorb thevolatile constituents in the feed fluid and transfer these vapors fromthe absorption column to the condenser stage where the vapors arecondensed and collected for use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration ofthe fluid purification system made in accordance with the principles ofthe invention;

FIG. 2 is a sectional view illustrating the liquid distributor sectionutilized in the system of FIG. 1 taken along the line 22 of FIG. 1;

FIG. 3 is a sectional view of the liquid distributor section of FIG. 2taken along the line 3-3 thereof;

FIG. 4 is a partial plan view of an exemplary absorbing curtain ofmonofilament Nylon fish net utilized in the system of FIG. 1;

FIG. 5 is a cross-sectional view illustrating the insulated chamber ofthe system of FIG. 1 taken along the line 55 thereof;

FIG. 6 is a graphicalrepresentation of the enthalpytemperaturecharacteristics of a liquid purification system used to explain theeffect of thermodynamic pinching;

FIG. 7 is a graphical representation of the enthalpytemperaturecharacteristics of a liquid purification system having an continuousbleed, semi-infinite stage transfer of a saturated gas from theevaporator section to the condenser section of the system; and

FIG. 8 is a reproduction of a portion of the graph of FIG. 7, drawn toan enlarged scale.

DETAILED DESCRIPTION Although the present invention has been describedwith water as a feed liquid, it should be understood that the system isapplicable to any liquid which can be cycled in accordance with theabsorption-evaporation techniques of the present system. Also, thesystem is described with reference to water at a temperature just belowthe boiling point under atmospheric pressure. However, the system willsuccessfully operate at lower temperatures, even as low as roomtemperature with subatmospheric pressure, or at higher temperaturesunder sufficient pressure as appropriate to maintain the heated fluid ina liquid state.

Referring now to FIG. 1, there is shown an exemplary embodiment of thecombination pure liquid extraction and feed fluid concentration systemmade in accordance with the principles of the invention. Feed liquid,such as sea water which is to be purified and concentrated in thesystem, travels through an inlet pipe 12 into a reservoir 14. The inletpipe 12 has a valve 16 (such as a float operated liquid level type) forregulat-. ing the amount of feed water to be fed into the system. Thereservoir 14 also contains a trap 18 and a blowdown valve 22 (which maybe controlled by a salinity controller 23) for draining the sump. Thetrap 18 is connected to the main portion of the reservoir 14 by means ofa weir 2S. Cooling coils 24 having an inlet 26 and an outlet 28 arepositioned in the sump for cooling the residual liquid in the reservoir14. The cooled residual liquid recycled with the fresh raw feed fluid ispumped from the reservoir 14 into a pipe 30 by means of a pump 32. Thefeed water then flows from the pump 32 into a pipe 36 and into amanifold 38 positioned on an insulated chamber 42 with side wall 43.

The central portion of the chamber 42 is divided by a transverselyextending barrier wall 44 positioned in a plane parallel to the sidewall 43 and contains a plurality of parallel connected condenser coils46, on one side of the barrier wall 44, with water from themanifold38,being distributed through the condenser coils. Typically, thecondenser coils may be formed of onequarter inch diameter coiledaluminum tubing. The water in the condenser coils 46 is pumped from thelower level input of the manifold 38 to a second manifold 48 positionedon the side wall 43 of the insulated chamber positioned near the chambertop wall 54.

The manifold 48 joins the output ends of the condenser coils 46 and thewater in the coils is then removed from the insulated chamber 42 andpassed through a heat source 56 which heats the water to a temperatureslightly below boiling, i.e. approximately F at sea level. The heatedwater is then coupled from the heat source 56 to a third manifold 62positioned on the side wall 64 of the insulated chamber 42 near the topwall 54. The heated water at the manifold 62 is then distributed througha plurality of parallel pipes 66 and transferred from the pipes 66 bymeans of capillary action (as will be explained in greater detailhereinafter) to sheets of spaced-apart mono-filament Nylon fish netting68.

The netting 68 hangs from just below the pipes 66 near the top of thechamber 42 and extends to a location in the chamber near the chamberbottom wall 72. An evaporator sump 74 defined between the bottom of thenetting 68 and the bottom wall 72 of the chamber where unpurified watercollects and is returned by gravity to the reservoir 14 by means of apipe 76 which connects the evaporator sump 74 and the reservoir 14.

The barrier wall 44 divides the central third of the chamber 42 andterminates at top edge 78. An opening 82 is defined by the edge 78 andthe chamber top wall 54. A branch wall 84 is formed at a downward acuteangle with the barrier wall 44 from the edge 78 and extends downwardlytoward the side wall 64 continuing as an interior bottom wall 86 spacedabove the chamber bottom wall 72. The branch wall 84 causes the netting68 to be bunched together near the evaporator sump 74.

Purified water which is formed in the chamber collects at the interiorbottom wall 86 and is transferred by means ofa pipe 92 which forms anopening 93 in the interior bottom wall 72 into a trap 94. The trap 94contains an opening 96 in the side wall thereof from which an outletpipe 98 is used to drain off the purified water into a fresh waterreservoir 100.

The side wall 43 of the insulated chamber 42 terminates below themanifold 38-and a curved side wall portion 102 extends outwardly and iscurved and forms a continuation of the chamber bottom wall 72. Theinterior bottom wall 86 is integral with an upward extension curvedportion 104 parallelling the curved side wall portion 102 so that afluid path 105 is defined between the interior bottom wall 86 and thechamber bottom wall 72 as well as the extension curved portion 104 andthe side wall portion 102. The interior bottom wall 86 and curvedextension portion 104 defines a condenser sump 109 thereabove and belowthe condenser coil 46.

The extension curved portion 104 of the wall terminates at a baffle 106which is spaced from thejunction of the side wall 43 and a horizontallyformed wall 107 which interconnects with one end of the curved side wallportion 102 and the lower end of the chamber side wall 43. Spaceddirectly above the baffle 106 is a tangential blower 108 which causesair to flow from the bottom of the condenser coil 46 through the fluidpath 105 in a direction shown by the arrows in FIG. 1 and upwardly intothe chamber 42 past the netting 68. Note that the blower 108 can beomitted and natural circulation relied upon for the air flow; however,some reduc tion in performance can result.

The barrier 44 extends across the width of the chamber 42 so as todivide the chamber into a condenser cooling section 112 formed of thecoils 46 and an absorption section 114 formed of the netting 68 as canbe seen in FIG. 5. The heated water which is transferred to the netting68 travels downwardly along the netting as the fluid in the system,normally air, is passed through the path and upwardly between andthrough the netting 68.

The circulated air becomes saturated with the hot water vapor andtravels so saturated through the opening 82 and into the cooling section112. The saturated air is cooled in the cooling section and fresh wateris precipitated therefrom into the condenser sump 109 downwardly towardthe interior bottom wall 86 whereupon it passes out through the pipe 92into the trap 94. Simultaneously, the circulated air passes back throughthe cooling section 112 to the blower 108 where it is recirculatedthrough the path 105. In place of air as a circulating medium, it shouldbe understood that other gaseous fluids which will absorb water can beused in the system when the system is closed with respect to the gaseousmaterial.

By leaving a large vertical opening 82 between the netting 68 and thecooling coils 46 at the top halfof the chamber, automatic continuous andprogressive bleeding at that region occurs as air will travel throughthe absorption material into the cooling coils along the height of theopening 82. Since the water cools as it travels down the netting 68, anarrower contact region is provided near the bottom of the opening 882where more restricted contact with the air is needed to aid insaturating the cooler air with cool water. A wider contact region isprovided with the air returned from the top of the netting 68 as thenetting bows outwardly towards the condenser section 112. In place ofthe single opening 82, one can interpose a plate with perforations orwith horizontal (or vertical) slots, or a louvercd plate, or the like,depending upon the nature of the fixed bed material, particularparameters desired, type of condenser surface, all in furtherance ofoptimization of a particular system configuration.

If a maximum concentration of the feed fluid is desired, the fluid path105 can be blocked and the curved side wall portion 102 can be openedfor exhaust to'the atmosphere by opening a first door 116 shown indotted lines. The door 116 is integrally formed with the wall portion102 and a second door 118 in the lower portion of wall 64 can be opened(as shown in dotted lines) so that the blower 108 admits fresh air intothe system at the bottom of absorption section 114. Thus, the opening ofthe first door 116 and the second door 118 increases the heat rejectioncapacity of the system by admitting fresh air into the system.

Furthermore, it can be seen from FIG. I that the system can functionsatisfactorily to extract purified liquids without the use of areservoir 14, cooling coils 24, a blowdown valve 22, a make-up valve 16or a pump 32 with the inlet pipe connected directly to the manifold 38.

Obviously, the doors 116 and 118 as well as the pump 32 and the coolingcoil 24 can be modulated to any degree separately or together toaccomplish maximum performance for any combination of purified liquidextraction and feed fluid concentration.

In addition to the overall counterflow arrangement of the absorptionsection 114, multipass cross-counter flow can be obtained by reorientingthe netting 68 perpendicular (edgewise) to the above mentioned slottedplate, and placing a multiplicity of horizontal baffles, slotted so asto mesh with the netting of curtains, to form a series of cross-bafflesfor guiding the vapor flow in a multipass cross-counter flow paththrough the netting without impeding the vertically falling liquidfilms.

Vapor bleed flow from the absorption section 114 to the condensersection 112 takes place via the slots in the vertical plate at selectedlocations where the interpass vertical portion of the vapor flow path isadjacent to the slotted plate. By these means, additional control ofvapor bleed and internal distribution in the absorption section can beobtained.

Referring now to FIG. 2, there is shown the interconnection between themanifold 62 and pipes 66 which transfer the heated water to the netting68. The pipes 66 are all connected in parallel in a plane parallel tothe top wall 54 of the insulated housing. Openings 122 are formed at thelower surface of the pipes which enable water to leak out of the pipeand spray downwardly. Capillary cloth 124 surrounds the outer surface ofeach pipe. The capillary cloth 124 saturates with water which istransferred to a flat portion 126 formed in a plane parallel to thepipes and directly therebelow.

Referring now to FIG. 3, a plurality of wicking members 128 isillustrated positioned directly below the flat portion 126 and areformed in a plane parallel to the pipes 66 but extend transverselythereto. The wicking members 128 are interspaced with a plurality ofsupport rods 132 which extend in the plane of the wicking members.The-wicking members 128 and support rods 132 are supported by means of asupport plate 134 which contains a plurality of openings 136 directlybelow each of the support rods 132.

The exemplary embodiment of the netting 68, illustrated in FIG. 4, isformed of a monofilament Nylon fishnet of diamond-shaped configurationand is hung on support rods as a group of parallel curtains with eachcurtain extending through the opening 136 downwardly toward thereservoir 74 as illustrated in FIG. 1 in planes generally parallel tothe condenser section. Alternatively, the netting can be hungperpendicularly (edgewise) to the condenser section 112 (not shown). Ina third configuration, the netting can be cut in the transversedirection and hung'as a multiplicity of coiled strands (not shown). Inthe latter two cases, the netting would not bow outwardly as in thearrangement of FIG. 1. The netting 68 is knitted, containing no knotstherein so as to enable the heated water to flow as a uniform film alongeach thread in every curtain toward the reservoir 74. Thus, heated wateris transferred from the pipe to the capillary cloth 124 and then to thewicking members 128 which in turn transfer the heated water to thenetting. Additionally, the heated feed water flows into the flat portion126 of the capillary cloth as the portion of the capillary cloth 124surrounding the pipes 66 saturates. The wicking members 128 are normallyhighly capillary and formed of a hydrophylic plastic fiber cord materialwhich acts as a liquid conductor. Suitable for use as the Nylon fishnetis U.S. Net and- Twine material, Stock No. 4, having one inch stretchmesh, 144 meshes deep, and made of single knot (knitted) virginmonofilament Nylon material.

Referring now to FIG. 5, there is shown a horizontal cross-sectionalarea of the chamber 42 taken along the line 5-5 of FIG. 1. Each of thenets 66 extends across the width of the chamber. By making the chamberwider, additional netting material of wider width can be utilized. Inaddition, by use of a plurality of parallel coils, additional coils 46can be added in parallel should it be so desired.

Referring now to FIG. 6, the thermodynamic processes involved in a waterpurification system can be described by means of an equilibriumline-operating line diagram which is plotted with the enthalpy (heatcontent) of a saturated mixture of air and water vapor as a function oftemperature. In FIG. 6, opcrationol' the water purification system isillustrated for an airwater system such as utilized in the purificationof salt water at one atmosphere pressure. The equilibrium lineillustrates the thermal energy content of moisture saturated air plottedagainst water temperature. Two equilibrium lines are shown; the solidline illustrating the case where saturated air over pure water occurs inthe condenser section, and the dotted line illustrating the case wheresaturated air over salt water exists in the evaporator section. Theoperating lines depict energy balances between the water and air streamsin the condenser section and the evaporator section. The example uses awater flow rate three times that of the air flow rate in the system.

In the first example, illustrated by operating line I, feed salt waterenters the condenser coils at 60F (point 1 of FIG. 6) and exits thecondenser coils at ll0F (point 2). The water is then heated to lF (point3) where it then enters the evaporator section. When the water leavesthe evaporator section, it has cooled to a temperature of F (point 4).if

Simultaneously, air flow from the bottom of the evaporator section at99F (point 1) leaves the evaporator at 143F (point a2) where it entersthe condenser section. As the air flows over the condenser coils it iscooled again to 99F (point a1) and returned to the lower end of theevaporator by a fan. Water is absorbed by the air in the evaporatorsection and removed from the air in the condenser section. Theperformance of the design illustrated by operating Line I isapproximately as follows:

Ratio of fresh product water to salt feed water 0.041; Number of effects0.76 The number of effects is defined as the ratio of the energyrequired to boil a unit mass of pure water to steam at one atmosphere,starting with a liquid at 60F, to the energy required by the process toproduce the same amount of pure water.

In a second example, illustrated by operating line II, performance wasimproved by making the unit twice as long. As a consequence, theoperating lines are closer to the equilibrium lines, with the result ofimproved performance. For the second example, the product water to feedwater ratios is 0.058 and the number of effects is 1.47. Any furtherincrease in size, or more ac curately, the number of transfer units,would not result in a significant increase in performance because theoperation lines would then be too close to the equilibrium lines at alocal point. This effect is called the thermodynamic pinch effect. Forthe two design cases illustrated in FIG. 6, the operating lines for thecondenser would eventually pinch at the water inlet and the operatinglines for the evaporator would pinch somewhere intermediate thereof.

An alternative design for circumventing the pinching effect can beaccomplished by changing the slope of the operating lines. By reducingthe water flow or alternatively increasing the air flow, the ratio ofwater to air flow can be made equal to unity. However, the limitingeffects of thermodynamic pinching will again be noticed.

A solution to the pinch problem would be to start a very low ratio ofliquid flow to air flow and gradually bleed air from the evaporator intothe condenser. In this way, the operating line can be made to follow theequilibrium line without pinching occurring. This solution requirescareful control of the bleed air flow which is an advantageous featureof the effective water purification by means of the present system.

The performance of an eight stage design is substantially better than asingle stage design described with respect to FIG. 6. With an eightstage design, the product feed water ratio is 0.093 and the number ofeffects is 5.20. Thus, for every pound of fresh water produced 10.7pounds of feed water is required, and 9.7 pounds of brine is rejected.The corresponding thermal energy input would be 215 BTUs per pound offresh water produced. A small additional amount of energy is requiredfor pumping power.

. When the concentration of dissolved solids in the feed fluid is highas a result of either the extraction of purified fluids and recyclingthe residual or from the use of an intially concentrated feed fluid suchas sea water, the evaporator equilibrium line is lower (less energy perunit mass of dry air). The water vapor pressure over the the moreconcentrated feed fluid is less because of the presence of moredissolved solids in the fluid. As a consequence, the operating lineswill tend to separate requiring an increase in the heat input orincrease in the evaporator size (number of transfer units) to maintainthe same output.

A fundamental feature of muIti-stage water purification is the method ofcontrolling the air bleed from the evaporator into the condenser byeffecting a bleed differential between the top and bottom of an openingformed in a divider plate between the condenser and evaporator. In thecase of a discrete number of stages such as an eight state design, bleedflow control may be obtained with a slotted or perforated divider platebetween the evaporator and the condenser. Continuous staging where theoperating lines are smooth curves that follow the equilibrium lines maybe obtained by using a more compact packing at the face of theevaporator. In essence, the resistance to flow in the evaporator can bevaried so that the desired bleed air flow control is inherentlyobtained. In designs utilizing the continuous staging, the curtains offishnet in the evaporator section are spaced closer together at the edgefacing the condenser than in the center thereof so as to obtain afurther regulation of the bleed flow.

FIG. 7 illustrates an equilibrium line operating line diagram for acontinuous bleed, semi-infinite stage design. With a sea water feed thisdesign, which is illustrated in FIG. 1 is thermodynamically ideal. Theproduct water and condenser tube wall temperatures are also shown inFIG. 8, which is an enlarged view of one porition of FIG. 7. The overallperformance of the system operating at the conditions shown in FIG. 7 isa product to feed water ratio of 0.10 and a number of effects of 8.5.Greater concentration of the sea water feed and a higher product to feedwater ratio can be achieved by recycling the concentrated brine (whichlowers the evaporator equilibrium line, and separates further theoperation lines) and by adding more thermal energy.

In the case of other solutions which are to be concentrated withcorresponding production of pure water, the performance of a system willdepend on the dissolved substances solubility and the vapor pressureover the solution. Carrier mediums other than air, (such as helium andhydrogen) may also be used. Mixtures of helium and oxygen also havecertain heat transfer and pumping power advantages. Pressure levelsother than one atmosphere (both higher and lower) are permissable.

The magnitude of the pressure change within the unit is a function ofthe air flow rate, the temperature, the rate of phase change(evaporation and condensation), the rate of molecular weight change andthe frictional and drag characteristics of the evaporator packing andcondenser coils. The bleed flow is proportional to:

(mAP/T) wherein;

m is the molecular weight of the air-water vapor mixture;

AP is the pressure differential between the evaporator and thecondenser; and

T is the temperature of the air-water vapor mixture at the locationwhere bleed flow was taking place.

The exponent K is 0.5 for turbulent flow and 1.0 for laminar flow. Bycareful design and experiment the bleed flow can be controlled eitherdirectly by using slotted or perforated plates or automatically by usingvariable packing in the evaporator section.

The use of compressed packing. (variable area) near the bottom of theevaporator, prior to bleeding of the air flow, is helpful to provideuniform flow in the evaporator packing and to help bring the operatinglines closer to the equilibrium lines (by increasing the number oftransfer units.)

When the design illustrated in FIG. 1 is operated with an open vaporcircuit so as to induct fresh air into the system, and the feed watercontains organic components, the oxygen in the fresh air could beutilized to bio-oxidize the organic components contained in the fluidbeing distilled.

The netting 68 can not only function as an absorption medium but also asa means for supporting a biological culture as well. Thus, the nettingcan serve as a trickling filter medium allowing excess culture growth toslough off into the sump 14 through the pipe 76 connected to theevaporator sump 74 to be settled and separated as a solid. Thesupernatant can be recycled into the system as usual. Of course, anyspecially prepared cultures can be utilized to enhance the results ofbiooxidation.

While the system has been illustrated as utilizing an external coolantin the sump cooling coils 24 to augment the cooling by the condensercoils 46 and an external heat source 56 which further heats the cooledwater from the condenser, it should be understood that the system can bemade to operate without these additional external heating and coolingmeans by utilizing a condensing unit as the heat source 56 and anevaporator unit as the sump coil 24, these being components of a vaporcompression refrigeration system and comprising a closed heat pump.Thus, the only energy input required would be to drive the refrigerantcompressor (not shown), fan 108, and the feed pump 32. Such anintegrated thermodynamic system could further reduce energy requirementsby at least two thirds.

The foregoing has described a unique system having a number ofadvantages over prior systems. Thus, all liquid flow is by gravity orvia capillary action and the liquid takes the form of thin films in theregions of mass exchange. Accordingly operation of the system conservespumping power, enables a high degree of separation, and provides a highdegree or surface contact, all in a simple vessel which can bephysically expanded or contracted to suit particular requirements.

I claim:

1. A vapor staging distillation system for separating liquid from feedmaterial, yielding a concentrate and a condensate comprising:

a vertically extending divider wall;

a vertically extending evaporation section on one side of said dividerwall;

a vertically extending condenser section on the other side of saiddivider wall;

cooling means for condensing vapor in said condenser section;

means for transferring said feed material to said evaporation section ata temperature higher than said cooling means; means in said evaporationsection for providing a plurality of vertically extending thin films ofliquid from said higher temperature feed material;

means for conveying a gas stream in cyclic flow from said condensersection to said evaporator section and back to said condenser;

said divider wall having an opening in the top portion thereofappreciable vertical extent, said evaporator and condenser sectionscommunicating directly through said opening whereby vapor from saidfilms in said evaporation section is conveyed by said gas to saidcondenser section to effect a bleed differential between the top andbottom of said opening;

means for collecting condensate from said condenser section; and

means for collecting concentrate from said evaporation section.

2. A system in accordance with claim 1 wherein said cooling meanscomprises a plurality of coils defining a flow path for said feedmaterial.

3. A system in accordance with claim 2 wherein said transferring meanscomprises a heat source for heating said feed material from said coolingmeans to a temperature near but below the boiling point of said liquid.

4. A system in accordance with claim 3 wherein the means for providingthin films in said evaporator section includes flexible, verticallyextending curtains of netting forming a fixed bed absorption column,said transferring means comprising means for feeding said feed materialto the top of said netting to form said thin liquid films.

5. A system in accordance with claim 4 wherein said netting is formed ofmonofilament Nylon fish net curtains.

6. A system in accordance with claim 4 wherein said netting forms ameans for supporting a biological culture.

7. A system in accordance with claim 4 wherein said means for feedingmaterial comprises at least one horizontally extending conduit connectedto a source of said feed material, said conduit defining openingstherethrough, and including capillary means contiguous with said conduitopenings and with the top of said netting whereby said feed material isconveyed from said conduit openings to said netting.

8. A system in accordance with claim 4 wherein said condenser coils andsaid netting are housed in an insulated chamber.

9. A system in accordance with claim 8 wherein said opening issubstantially uninterupted to provide continuous gas and vapor transfer.

10. A system in accordance with claim 8 wherein said divider wall isformed to bunch said netting at the bottom portion thereof whereby saidnetting bows toward said condenser section through said divider wallopening.

1. A vapor staging distillation system for separating liquid from feedmaterial, yielding a concentrate and a condensate comprising: avertically extending divider wall; a vertically extending evaporationsection on one side of said divider wall; a vertically extendingcondenser section on the other side of said divider wall; cooling meansfor condensing vapor in said condenser section; means for transferringsaid feed material to said evaporation section at a temperature higherthan said cooling means; means in said evaporation section for providinga plurality of vertically extending thin films of liquid from saidhigher temperature feed material; means for conveying a gas stream incyclic flow from said condenser section to said evaporator section andback to said condenser; said divider wall having an opening in the topportion thereof appreciable vertical extent, said evaporator andcondenser sections communicating directly through said opening wherebyvapor from said films in said evaporation section is conveyed by saidgas to said condenser section to effect a bleed differential between thetop and bottom of said opening; means for collecting condensate fromsaid condenser section; and means for collecting concentrate from saidevaporation section.
 2. A system in accordance with claim 1 wherein saidcooling means comprises a plurality of coils defining a flow path forsaid feed material.
 3. A system in accordance with claim 2 wherein saidtransferring means comprises a heat source for heating said feedmaterial from said cooling means to a temperature near but below theboiling point of said liquid.
 4. A system in accordance with claim 3wherein the means for providing thin films in said evaporator sectionincludes flexible, vertically extending curtains of netting forming afixed bed absorption column, said transferring means comprising meansfor feeding said feed material to the top of said netting to form saidthin liquid films.
 5. A system in accordance with claim 4 wherein saidnetting is formed of monofilament Nylon fish net curtains.
 6. A systemin accordance with claim 4 wherein said netting forms a means forsupporting a biological culture.
 7. A system in accordance with claim 4wherein said means for feeding material comprises at least onehorizontally extending conduit connected to a source of said feedmaterial, said conduit defining openings therethrough, and includingcapillary means contiguous with said conduit openings and with the topof said netting whereby said feed material is conveyed from said conduitopenings to said netting.
 8. A system in accordance with claim 4 whereinsaid condenser coils and said netting are housed in an insulatedchamber.
 9. A system in accordance with claim 8 wherein said opening issubstantially uninterupted to provide continuous gas and vapor transfer.10. A system in accordance with claim 8 wherein said divider wall isformed to bunch said netting at the bottom portion thereof whereby saidnetting bows toward said condenser section through said divider wallopening.